Reverberatory furnace for melting metals



June 6, v195o 'w. F. sKLENAR Rnvmm'ronv FuRwAcx-z Fon Emma METALS v Filed April 25, 1946 I N/ENTOR': )klamm ATI'QRNEY June',A 1950 w.F. sKLENAR A 425105352,

. REVERBERATORY FURNACE FoR HELTING METALS Fileq April 25.194@V s sheets-snaai s n ATTORNEY June 6, 1950.- w.'|'. svKLENAR y l REVERBERATORY FURNACE FUR IELTING Filed April 25., 1946 '5' Sheets-Sheet 4 'ATTURNFY Patented June 6, 1950 v 2,510,352 REVERBERATORY FURNACE Foa MELTING METALS WenzeslawFrank Sklenar, Chicago, Ill., assignor of one-fourth to John H. Ehardt, Chicago, Ill.

Application April 25, 1946, Serial No. 664,8'65

(Cl. 26S-33) 4 Claims.

The present invention relates to reverberatory furnaces, and is particularly concerned with metal melting furnaces of the type covered by my prior patent, No. 1,823,005, Reverberatory furnace, issued September 15, 1931, and constituting a revolutionary improved process and apparatus for the melting of metal of high quality, with greater efficiency, shorter time, and less man power.

One of the objects of the invention is the provision of an improved reverberatory furnace for melting metals, which is adapted to produce a higher quality of molten metal, accomplish the melting ina much shorter time, with a considerable reduction in the use of fuel, a marked elimination of waste, and a saving in labor hours required.

Another obj ect of the invention is the provision of an improved melting process and an improved process for the generation of maximum heat and its application to metal to be molten, by means of which metal may be melted more quickly, more cleanly, with less fuel and less labor than any of the devices of the prior art.

Another object of the invention is the provision of -an improved reverberatory furnace structure which is provided with a plurality of removable and adjustable archv units adapted to be so located in the roof of the reverberatory furnace that their effect in reflecting and radiating heat toward the bath of metal is a maximum, and they are also adapted to deflect, at a multiplicity of different points, the hot combustion gases to the surface of the metal, thereby causing such a turbulence of the gases that a maximum engagement of the gases and the metal is accomplished, while still passing the gases through the furnace in large volume and at high velocity, and concentrating the hottest gases at the melting zone of the chamber to effect a quick melting.

Another object of the invention is the provision of an improved reverberatory furnace structure which has its bed and side Walls so constructed that they may be used for many more heats than the furnaces of the prior art, and having its roof composed of a multiplicity of removable and adjustable arch units, which may be lifted from their supports on the side walls so that the arch units may be repaired between melts and so that the rest of the furnace lining is also available for repair whenever necessary, which is required only at relatively long intervals.

Another object of the invention is the provision of an improved reverberatory furnace of the class described, the roof of which is provided with a multiplicity of downwardly projecting abruptv shoulders or obstructions adapted to be engaged by the hot combustion gases for heating the roof, brick work and for kdeflecting the hot combustion gases downward toward the surface of the metal and causing a maximum contact between the gasesl and the metal, the said furnace also including refractory lined conduits located about the uptake or chimney end of the furnace, and adapted to be used for preheating air that is used not only for mixture with the combustion gases or other fuel, but which is also introduced into an elongated combustion chamber to augment and intensify the combustion flame by adding heated oxygen to effect a more complete combustion of the gaseous combustible products stili remaining after the initial stages of combustion of the fuel.

Another object of the invention is to provide an improved reverberatory furnace of the class described which is particularly adapted to be used for holding metals requiring a high melting temperature, such as steel, malleable'iron, copper, nickel alloys, iron, ferro-manganese alloys, etc.

The present invention preferably comprises a reverberatory furnace of the tilting type; but in l some embodiments of the invention the furnace may be constructed in thestationary type. The furnaces embodying the invention preferably include one or more of the following elements or features in combination with others of these features, as set forth in the appended claims, which are appended for the purpose of distinctly claiming and pointing out the novel combinations comprising the invention.

For example, the apparatus made according to this invention may include a suitably-shaped elongated metal shell having a rounded bottom provided with two or more concentrically extending tracks mounted upon rollers flanged to guide the tracks, to permit the tilting of the furnace for the discharge of its content, the shell being lined with a plurality of layers of firebrick, forming on the bottom a relatively elongated and shallow cavity for receiving the molten metal, the sides of the shell extending upwardly and being similarly lined with a'plurality of layers of iirebrick and beginning at the burner end, with a roof of rebrick forming a burner opening and an elongated combustion chamber tapering backwardly toward the burner and increasing in size toward the medial part of the furnace, the said furnace being provided with a roof comprising a plurality of arch units supported at successively lower levels as they are located backwardly in the furnace. to increase the restriction between the roof and the metal and to form a multiplicity of downwardly projecting abrupt shoulders to be engaged by the combustion gases; the furnace preferably includes an uptake or chimney at its rear end practically surrounded by a. wall containing refractory lined conduits extending backwardly and forwardly around three of the walls of the uptake to conduct air from a blower which\is to be preheated and used for the air of combustion mixed with the fuel before the nozzle, and also introduced into the combustion chamber through the roof, through a plurality of conduits in such manner as to deflect the hot combustion gases downward and to supply the additional heated oxygen which intensifies the combustion and causes a further combustion of the carbon elements which would otherwise be wasted in the form of gases.

My process of melting metals preferably comprises charging the metal to be melted into a hopper at the gaseous discharge end of a furnace in suitable small increments, such as shovelfuls continuously, while the heated gases of combustion are passing between the solid particles, which are arrested at a suitable restriction which is located rearwardly of the hottest part of the furnace, the combustion gases at the point of discharge also heating a supply of air under pressure in contact with the walls of the chimney, the heated air being carried to the forward part of the furnace and mixed with a predetermined amount of combustible fuel and injected' by a flaming burner into a widening combustion chamber, an additional supply of air under pressure being driven under pressure from a plurality of openings in the insulated furnace wall into the combustion chamber at a point remote from the burner and transversely to the wall from the burner to intensify and perfect the combustion, the hot combustion gases from the burner being directed at a point between the bottom of the furnace and the said restriction, which is rearwardly of the hottest point in the furnace, the hot combustion gases being deflected downwardly toward a bed of metal in the furnace a multiplicity of times successively by abrupt shoulders extending transversely of the flow from the burner to the outlet and depending from the roof of the furnace, the said abrupt shoulders being carried by a plurality of movable arch units which are adjusted in elevation to provide a maximum application of heat to the bed of metal by deflection and radiation of heat from the arches, whereby a supply of metal is quickly melted and maintained in a clean condition.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the five sheets of drawings accompanying the specification:

Fig. 1 is a side elevational view of a reverberatory furnace embodying the invention, and particularly adapted to be utilized for melting the high melting point metals mentioned above, the side plate being partially broken away to show the internal structure;

Fig. 2 is the top plan view, shown in partial section, the top panel being broken away at the lower part of the figure to show the top of the arch units, and the section being taken below the top wall or roof at the upper part of the figure to show the structure of the furnace;

Fig. 3 is a longitudinal vertical sectional view. taken on the plane of the line 3-3 of Fig. 2,1ooking in the direction of the arrows;

Fig. 4 is a transverse vertical sectional view, taken o the plane of the line 4-4 of Fig. 3, looking in the direction of the arrows;

Fig. 5 is a fragmentary sectional view, taken through a portion of the furnace walls to illustrate another form of removable arch unit;

Fig. 6 is a fragmentary sectional view, taken on the plane of the line 6-6 of Fig. 3, looking in the direction of the arrows.

The reverberatory furnace, which is indicated in its entirety by the numeral I0, preferably includes an external metal shell I I, which is lined with a suitable refractory, such as the iirebrlck lining Which is indicated in its entirety by the numeral I2.

The shell I0 has its bottom member I3 curved laterally and provided with a pair of curved tracks I4, I5, which are either of the same radius or concentric, and each track is mounted upon a pair of rollers I6, I1 carried by a lower rectangular framework I8.

Thus the rear pair of rollers I1 are shown supporting the track I5 in Fig. 4 in such manner that the entire furnace assembly I0 may be caused to rotate about an axis, which is the center of curvature of the bottom wall I3 of the shell.

The rollers I6, I1 are provided with suitable guide flanges 20 and the tracks I4, I5 with suitable stops 2I, 22 on each side of the furnace, as shown in Figs. 1 and 4, the right hand stop being hidden by the discharge spout 23.

The bottom wall I3 of the metal shell is joined to the upwardly extending parallel side walls 24, 25; and the shell walls I3, 24, 25 are preferably lined with a suitable refractory, such as a pair of courses 26, 21 of flrebrlck suitably curved to engage the bottom wall I3 and to form a shallow bed for receiving molten metal.

The nozzle opening 23 is formed by suitably shaped nrebrick supported by an extension 28 of the bottom shell I3 and provided above with an inspection door 29 suitably hinged, and provided with an external metal shell 30 and ilrebrick insulation 3|.

'Ihe side Walls 24, 25 and firebrick 26, 21 extend upwardly to a. minimum height at which the roof is intended to be supported upon the upper flat Wall surfaces 32, 33.

In addition to the central transversely curved portion I3 of the bottom shell, the furnace shell is preferably elongated from front to back, and the bottom tapers upwardly at 34 (Fig. 3) toward a front wall 35, which is provided with a suitable burner opening 36.

At this end of the furnace the rebriick formv a combustion chamber 31, which becomes wider toward the rear of the furnace and tapers toward the burner opening 36, being surrounded by the rebrick 26, 21 on the bottom and sides and by a, suitable roong 38 of rebrick.

In embodiments of the invention which are intended to melt the high melting point metals a predetermined number of roof bricks 38 are provided with the through bores 39 (Fig. 3) and Fig. 6, regularly spaced from each other and arranged transversely of the combustion chamber 31 adjacent its larger end.

These through bores 39 communicate with larger counterbores 40 for receiving the hot air pipes 4I, which extend downwardly from a mani- 76 fold or distributor pipe 4'2, having a closed end ing intoone end lof the conduit 50.

4l. The conduits 19 are adapted to discharge superheated air into the combustion chamber I1 at a point where ordinary combustion would be substantially completed, but certain combustible matters are still present in the gases of combustion, such as carbon monoxide and small particles of carbonaceous d-ust or soot, lwhich are also to be burned to intensify and perfect the combustion.

At the opposite end of the bottom shell I3 this bottom shell is provided with an upwardly curved rear wall 44 suitably lined with a pair 54 on the top shell andadapted to be moved upwardly, as shown in Fig. 3,v to permit the chimney opening 41 to be used as a hopper in charging the furnace with metal to be molten.

When the complete charge has been placed inside, which is preferably done in small increments, such as shovelfuls, continuously, the grille y 53 is again placed in the closed full line position.

of Fig. '3 to provide a. suitable restriction for the opening 41 by means of its cross bars 55, which provide openings between them at 56 of limited area.

This tends to continue to restrict the discharge gases in a. manner similar to the restriction encountered when the combustion gases are passing through a, body of pieces of metal to be molten so that the melting operation will still continue in the same manner without too free passage of the combustion gases fromthe uptake.

The flrebrick 48, 50 located about the two sides and rear of the hopper opening" are preferably formed with a multiplicity of hot air passages 51-60, each passage extending along the side panel' 52 across the back 52a and forwardly at the side panel 5I, with only a relatively thin.

flrebrick between the conduits 51-60 and the chimney opening 41.

These conduits 51-60 are connected in a continuous circuit beginning With'a blower discharg- The latter communicates at its other end with a conduit 58, and the `conduit 58' communicates at its opposite end with conduit 51.

Conduit 51 is indicated in Fig. 2, and is connected with a suitable conduit or pipe 6I leading the hot air forwardly to be discharged into the distributor manifold 42 and also into the fuel pipe 62 of the burner 63.

Air pipe 6I is provided with a suitable valve 64, and the fuel pipe 62 is also provided with a suitable valve so that a predetermined mixture of fuel and air is provided for the burner 63, both being 'discharged under a predeterminedI pressure.

Various kinds of fuel may be employed, such as gas, fuel, oil,.pulverized fuel, such as coke, or the like, the oil being suitably atomized -by an oil nozzle located inwardly of the burner nozzle 63. The burner nozzle 63 is preferably located to point downwardly and rearwardly toward the middle of the hottest zone 65 of the furnace, which is located just rearwardly of the restriction 66 formed by the rear arch unit 68.

The charge which is placed in the chimney or hopper 41 falls downwardly and forwardly on the curved bottom portion 68 (Fig. 3), and piling..

-up in its natural angle of repose, soon engages the restriction at 66 or the restriction at the firefbrick of the rearA wall 61 to form a porous mass lhopper 41 the roof of the furnace is preferably 10 formed out of a multiplicity of arch units 68,

69, 10,.1I, and others, if desired. All of these arch units `may be of similar constructioni in the present specification and claims I employ the word arch as a genericterm for describing theroof units made of iirebrlck which are held in a unit assembly by being pressed against each other, irrespective of the shape of the roof surface, which may be straight, as indicated at 12 inFlg. 5, or curved as indicated at 13, 14, 15 in Fig. 4.

Where afurnace -is relatively narrow and small, it is possible to simplify the construction by utilizing the straight roofed arch units of the type illustrated at 16 in Fig. 5 with a plane lower surface 12; but where the furnace is relatively wide or large, it is necessary to utilize larch unitshaving a. curved lower surface, as exemplified at 13,14, 15 in Fig. 4.

In either event the archvunits comprise, as shown in Fig. 5, a multiplicity of rebricks 11,

I preferably of the type having tongue and groove connections between bricks, which prevents them from getting out of alignment with each other; and the flrebricks 11 are confined between the end plates 18, 19 of metal.

Firebricks 11 are also clamped between the end plates 18, 19 by means of a plurality of `transverse tie bolts threaded at one` or both ends and provided with a head 3| and nut 82 to place y such 'a pressure on the firebrick that the arch as sembly forms aunit.

Such a unit is readily removable; and as the frames are directed against the lower and forward parts of the arch units, these units receive the most wear, and may need repair or replacement after a long interval of time, such as, for example, one hundred heats. 1 l

The arch units 16 can be removed during heats and replaced by others which are new or repaired; and when removed, the entire interior of the furnace is accessible for repair of any portion of the rebrick wall.

- In order to provide for their convenient removal each tie bolt may be provided with a pair of U-shaped lifting stirrups 83, having its lower ends welded to the tie bolts, such as tie bolt 80; and by means of a suitable chain hoist or other hoist the arch units 16 may be removed or replaced with a minimum amount of labor.

In order to secure the arch units in place the side panels 24, 25 of the shell` may be provided with horizontally extending angle irons 84, having apertures for receiving the securing bolts, which also pass through lugs carried by the end plates 18,

The bolts 86 are long enough so as to permit adjustment of the' arch units 16 upward or downward by inserting or removing bricks or half or quarter bricks, or by using a layer of initially plastic refractory to accomplish the placement desired, as shown at 81 in Fig. 4.

As the elevation of the arches decreases from the front or burner end of the furnace toward the rear or chimney end, the elevation of the angle irons 84, to which the arch units are bolted by wardly of the furnace.

Thus the arch section 1| is stepped downwardly with respect to the upper wall 38 of the combustion chamber 31, providing an abrupt shoulder at 88, opposing the flame from the burner nozzle 63 and tending to dei-lect it downward toward the bath of metal, the level of which is indicated at 89.

The elevations of the arch units may be varied, depending upon the material to be molten, the temperature at which it melts, the fuel used, etc. to secure the best results; and in some instances two or more of the arch units, such as 10, 1|, may be at the same level, as shown in Fig. 3.

In this example the arch unit 69 also presents an abrupt shoulder 90 forwardly toward the llame from the burner 63; and the flame and products of combustion, which are deflected downwardly to the surface of the metal by the shoulder 88, may be deflected upwardly against the shoulder 90 again by the metal.

This shoulder again has a tendency to deflect some of the gases downwardly toward the surface of the metal 89, which` again deflect the flame and hot combustion gases upwardly against the forwardly facing shoulder 9| on the arch unit 68. From this deflecting surface the gases are again deflected downwardly toward the metal beneath the arch unit 68 and upwardly toward the pile, l

the charge for which is located at the restriction 66.

Referring to Fig. 4, the form of curved arch unit here illustrated is the same as that employed at 68--1I in Fig. 3. The forwardly facing shoulders 9| and 90 are visible, as the section is taken at the discharge spout 23. This form of arch unit 68-1I preferably has its end plates 92, 93 provided with an inwardly extending horizontal flange 94, 95 adapted to confine the end blocksV 96, 91 of the arch not only at their sides, but at their bottoms.

The initially plastic refractory at 81 insulates the edges of the lower flanges 94,` 95 from the gases of combustion. The arches may be spaced upwardly or downwardly, as required by conditions, to secure a maximum radiationV of heat from the flrebrick of the arches to the bath of metal and to deflect the gases downwardly in a most effective manner at each of the abrupt obstructions 88, 90, 9|, etc.

The end blocks 96, 91 of a curved arch are engaged by a multiplicity of wedge-shaped bricks 98 curved above and below, and preferably provided with tongue and groove projections also for holding them in alignment. Such an arch structure is again clamped by means of the same tie bolts 80, having the lifting U-shaped loops 83, and passing through the end plates 92, 93.

The top of the furnace is preferably enclosed by a top panel 99 secured to a suitable rectangular framework I 00, which is carried by the upper end wall at the front end of the furnace, and by the chimney wall |02 at the rear end of the furnace.

Suitable side panels |03, |04 (Fig. 4) may enclose and cover the bolt connections for removable arch units; and the space between the side panels |03, |04 and the plates 92, 93 may be filled with insulation |05, such as asbestos, while the I R 8 top of each arch is covered with initially plastic insulation, such as llre clay |08.

The present method of melting metals with the foregoing apparatus may be outlined briefly as follows: The burner nozzle is supplied with one of the fuels mentioned, such as gas, in a suitable amount, as regulated by the valve, and with air in suitable amount, as regulated by the valve, the air having been preheated by being passed through the conduits located around the uptake of the furnace, after the furnacegitself has first been subjected to a period of preheating by means of the burner, with the uptake grille closed.

A suitable charge of metal to be melted is placed in the hopper of the furnace, after the furnace has been preheated, the solid metal being deposited in small increments, such as shovelfuls. The

.size of the restriction at the lower end of the uptake is such that the metal to be molten piles up and presents a porous mass vthrough which the hot gases of combustion pass, preheating the.

solidmetal, the melting taking place at the forward end of this pile or mass of metal, and the molten metal running down into the concavity at the bottom of the furnace.

The flame from the burner is directed downwardly and rearwardly in the reverberatory furnace toward a medial point toward the bottom and the restriction at the uptake, this being the hottest part of the furnace; but there is a considerable amount of spread of the flame, and some of the flame is immediately directed from the burner downwardly toward the molten metal in the furnace, while the upper part of the flame impinges upon the abrupt forward edge 88 of the first arch unit.

These portions of the combustible gases are deflected downwardly, and at the same time an additional supply of air is passed into the roof of the furnace at the 'rearend of the combustion chamber through the tuyres 39, intensifying the combustion by supplying the name at this point with heated oxygen, which produces more perfect combustion by burning up the carbon monoxide and solid particles of soot or other carbonaceous materials still existing in the hot combustion gaSeS.

The hot gases deflected downwardly toward the metal surface 89 are again reflected upwardly into engagement with the abrupt shoulder 90 of the arch 69, where they are again deflected downwardly to the metal and upwardly into engagement with the abrupt shoulder 9|.

This shoulder deects the gases downwardly Y again toward the metal, and they. then pass into thehottest part of the furnace and proceed with the melting of such portion of the charge as faces forwardly, the rest of the solid charge dropping downwardly in the hopper or chimney as the melting progresses. v

Although the furnace is most efficiently operated when a charge is used which is suitable for its capacity, such as a 1,000 pound charge for a 1,000 pound furnace, the present furnace is also adapted to handle lesser charges and to melt them in a proportionately smaller time, as the procedure is the same, except that a lesser number of increments of the solid charge are placed in the chimney. After all of the metal is melted, the grille 53, which is a device for restricting the escapinggases passing out of the furnace after all of the metalrhas been charged and dropped to the bottom of the hopper, should be closed.

This will retain the maximum of heat in the maximum amount of heat in the furnace, withl a minimum amount of fuel.

The adjustability of the archv units vpermits them to be so arranged for the particular metal in question that a maximum heat and deflection of gases to the hearth is secured; and radiation from the brickwork of the arches to the hearth is another important factor contributing to the maintenance of the necessary temperature of the metal. f

In addition to being easily adjusted for adaptlng the furnace to ge melting of any particular Anetal in question,vl e arch units are easily removable, permitting easy access to thefurnace for repairs and replacement, which are very common and troublesome occurrences in all high temperature melting furnaces, rendering great difllculty where fixed arch construction is employed.

Replacement vof the arches and the hearth, or repair with silica, sand,` or other material can be easily carried out, even between melting, when the furnace has been emptied of its contents, if it is absolutely necessary to do so.

The speed of passage of the gases through the reverberatory furnace is a matter of the utmost importance, especially with high zinc alloys, or in the case of melting borings and turnings; and this speed may be regulated by the input of air and gas at the burner and at the tuyres, and by the height of the arches, particularly the bottom of the arch forming the bottom of the hopper at the restriction 66.

One of the most important features of the present invention is the speed and emciency with which metal is melted, utilizing less fuel and accomplishing its work in materially less time than any of the furnaces of the prior art, and producing a molten metal of more superior characteristics than any of the furnaces of the prior art. For example, a crucible furnace utilizing expensive crucible pots, the thousand pound size costs about $100.00; and the life of the crucible varies from fifteen to about forty heats; whereas the present furnace will give one hundred heats service on melting high duty iron alloys. Even after this period of service, it is only necessary to replace the lowermost hopper arch, which may be accomplished in a matter of a few minutes; and each weekend a little attention is given to the walls, where necessary, and this is easily done by lifting the arches to render all of the walls and the hearth accessible.

The crucible furnace of a thousand pound sizev copper alloy, and will melt it in from one and one-half to one and three-quarters hours, requiring between two and two and one-half gallons of fuel oil for each one hundred pounds of metal melted. l

An electric furnace, which is commonly supposed to be the ideal mode 'of melting metal,

produces a very high quality of metal, but at a very high operating cost, the favorite size of furnace being about eight hundred pounds, and the melting time being fifty-five minutes.

The upkeep of all of the above-mentioned furnaces is very dimcult and expensive, while the upkeep of a furnace embodying my invention is very simple and relatively inexpensive.

Comparing my furnace with the foregoing examples, the present reverberatory furnace of the thousand pound size will melt a full charge of one thousand pounds of any bronze or copper alloy in from fifteen to twenty minutes from the time of charging to pouring; and the fuel consumption is onegallon of oil for one hundred pounds` of metal.

This thousand pound size of my reverberatory furnace has sufficient capacity to replace three barrel furnaces of eight hundred pounds capacity, one electric furnace of eight hundred pound capacity, and two pit vfires of two-hundred and fifty pound capacity each, and at the same time reduce the labor from six men to two.

The composition of metal which is melted in my furnace is comparable in every way to that of the metal melted in an electric furnace, but is far superior to metal melted by any of the other methods. For example, metal melted by other methods than electric furnaces or my furnace may have a tensile strength of thirty thousand pounds per square inch and an elongation of twenty percent. If the same metal is melted according to.

my process, its tensile strength will be thirtyfour thousand pounds per square inch and its elongation will be thirty-five percent.

The metal prepared by my furnace also provides castings having a very fine, close grain of the highest physical tests; and impurities picked up from coke or from the combustion gases, such as sulphur, phosphorus, and other impurities are absent.

Comparing my method of melting iron, for example, with the common practice of melting iron in a cupola, in this common practice the metal is charged intermittently with coke. This melting is thus made quite rapid, but the metal is percolating through the coke and picking up carbon, phosphorus, sulphur, and other impurities; and such metal can be used for` crude purposes only. It is not possible to obtain a high quality ofj iron alloy when the melting is accomplished in a cupola, and several hours must be spent in patching the burned away wall each day.

The present reverberatory furnace will produce the highest quality of iron alloys in batches of one thousand pounds every forty to forty-five minutes, the resulting castings having a very ne,

may, therefore, be'summarized briefly as follows:

1. Greater flexibility with perfect control; 2. Fifty percent lower fuel consumption;

il A 3. Seventy-five percent savings in labor cost;

4. Faster melting in a fraction of time required by other furnaces, resulting in greater output with less equipment; 5. Superior metal, both chemically and physically;

6. Elimination of costly crucibles and costly and diiiicult furnace repairs;

7. Lower metal losses. f

One of the most important features of the invention is the elongation of the furnace and its width as compared to the vdepth of metal in the furnace. combined with the high velocity of the flame and combustion gases passing through this elongated chamber, presenting the maximum area of metal to the combustion gases for heating the metal which is melted and which conducts heat to the solid metal which is in a pasty condition or in a solid condition at the restriction in the furnace.

Not only does this arrangement provide a far greater area of contact between the hot combustion gases and the metal, but it brings the roof closer to the top of the metal to radiate heat from the rebrick of the roof to the metal, and the high velocity of the gases effectively drive the heat to the far end of the furnace, where the charge is placed, in front of which is located the hottest point of the furnace.

yWhile I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims. V

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a reverberatory furnace, the combination of a support with a tiltably mounted metal shell, the said shell being provided with a discharge opening atI one side, a burner opening at one end and a combined hopper and chimney at the opposite end., the said shell being curved longitudinally and provided with its lowest point adjacent said discharge opening, and having a lining of nre-brick along its bottom and upwardly around said chimney and upwardly on both sides to form insulated side walls, the said side walls being stepped downwardly at a plurality of points to successively lower upper surfaces from said burner opening to said chimney, and a plurality of removable arch members comprising units mounted upon the stepped surfaces of said side walls and presenting forwardly facing shoulders at the ceiling of the furnace, each of said arch members comprising an angle iron at each end, having an inwardly turned flange and a vertical flange, and including a plurality of brick arches, the end bricks of each arch resting upon said inwardly turned flanges. and tie bars extending between and passing-through said vertical flanges and provided with threads and threaded members for clamping the angle irons upon the bricks of the arches for maintaining the removable arch units in unitary condition for removal and repair.

2. In a reverberatory furnace, the combination of a support with a tiltably mounted metal shell, the said shell being provided with a discharge opening at one side, a burner opening at one end and a combined hopper and chimney at the opposite end, the said shell being curved longitudinally and provided with its lowest point 12 adjacent said discharge opening, and having a lining of nre-brick along its bottom and upwardly around said chimney and upwardly on both sides to form insulated side walls, the said side walls being stepped downwardly at a plurality of points to successively lower upper surfaces from said burner opening to said chimney, and a plurality of removable arch members comprising units mounted upon the stepped surfaces of said side walls and presenting forwardly facing shoulders at the ceiling of the furnace, each of said arch members comprising an angle iron at each end, having an inwardly turned ange and a vertical fiange, and 'including a plurality of brick arches, the end bricks of each arch resting upon said inwardly turned flanges, and tie bars ex tending between and passing through said vertical iianges and provided with threads and threaded members for clamping the angle irons upon the bricks of the arches for maintaining the removable arch units in unitary condition -for removal and repair, the said tie bars being provided with a pair of U-shaped lifting members having the ends of the legs of the U-shaped members welded to the tie bars, and the U-shaped members being located adjacent the ends of the tie bars.

3. In a reverberatory furnace, the combination of a support with a tiltably mounted metal shell, the said shell being provided with a discharge opening at one side, a burner opening at one end and a combined hopper and chimney at the opposite end, the said shell being curved longitudinally and provided with its lowest point adjacent said discharge opening, and having a lining of fire-brick along its bottom and upwardly around said chimney and upwardly on both sides to form insulated side walls, the said sidewalls being stepped downwardly at a plurality of points to successively lower upper surfaces from said burner opening to said chimney, and a plurality of removable arch members comprising units mounted upon the stepped surfaces of said side walls and presenting forwardly facing shoulders at the ceiling of the furnace, each of said arch members comprising an angle iron at each end, having an inwardly turned flange and a vertical ange, and including a plurality` of brick arches, the end bricks of each arch resting upon saidinwardly turned flanges, and tie bars extending between and passing through said vertical fianges and provided with threads and threaded members for clamping the angle irons upon the bricks of the arches for maintaining the removable arch units in unitary condition for removal and repair, the said vertical ilanges and the said shell being provided with outwardly projecting securing flanges, having apertures in alignment with each other and threaded members extending through said apertures for clamping the arch units to said shell.

4. In. a reverberatory furnace, the combination of a support with a tiltably mounted metal shell, the said shell being provided with a discharge opening at one side, a burner opening at one end and a combined hopper and chimney at Vthe opposite end, the said shell being curved longitudinally and provided with its lowest point adjacent said discharge opening, and having a lining of fire-brick along its bottom and upwardly around said chimney and upwardly on both sides to form insulated side walls, the said side walls being stepped downwardly at a plurality of points to successively lower upper surfaces y 13 from said burner opening to said chimney. and a plurality of removable arch members comprising units mounted upon the stepped surfaces of said side walls and presentinglorwardly facing shoulders at the ceiling of the `furnace, each of said arch members comprising an angle iron at each end, having an inwardly turned ilange and a vertical flange, and including a plurality of brick arches, the end bricks lof each arch resting upon said inwardly turned flanges. and tie bars extending between and passing through said vertical ilanges and provided with threads and threaded members for clamping the angle irons upon the bricks o! the arches for maintaining the removable arch units in unitary condition for removal and repair. the said `furnace being provided at its burner end with a conical'outwardly tapering combustion chamber for receiving the burner blast, and with a plurality of hot air conduits extending into the upper part oi' said combustion chamber atl a point spaced from the, burner. the said hot air conduits being connected by a manifold and conduit to air heating conduits located in the wall of said chimney.

W FRANK SKLENAR.

14 REFERENCES CITED The following references are of record in the le oi this patent:

UNITED sTATEs PATENTS Y Number Name Date 403,152 vSleicher May 14, 1889 1,266,745 Wundrack May 21, 1918 1,344,437 Buell June 22, 1920 1,376,482 Thomas May 3, 1921 1,420,312 Grindle June 20, 1922 1,590,373 Holbeck June 29, 1926 1,696,794 Curtis Dec. 25, 1928- 1,751,675 Abbott Mar, 25, 1930 1,900,942 McCutcheon Mar. 14, 1933 1,983,927 Bent et al Dec. 11, 1934 2,065,691 Hanson et al. Dec. 29, 1936 2,139,172 Nicholas Dec. 6, -1936 2,182,674 Morton Dec, 5, 1939. 2,414,545 Moore Jan. 21, 1947 FOREIGN PATENTS Number i Country Date 370,636 GreatBritain Apr. 14, 1932 562,407 Great Britain June 30, 1944 148,540 Switzerland Oct. 16, 1931 

